example to try to convey what I do not understand.

Say the catcher is standing/sitting/kneeling on the plate completely blocking it.
The catcher receives the ball, and the runner is 20 feet away from the plate when the catcher receives the ball.
The catcher never moves.
The runner arrives at the plate much later and is tagged out.
Is this obstruction? I am assuming no because the runner was so far away when the catcher received the ball. If so, this implies the position of the runner is important. If the position of the runner is important, then can you explain to me in what way the position of the runner is important?

Now, if the above is obstruction, then it implies the position of the runner is not material (and clearly UL should have been called for obstruction).